The present invention relates to a method of printing a graphic on an electronic memory card.
A particularly advantageous application of the invention lies in the field of memory cards of the type comprising a card body with an electronic module mounted on it. The card body has two main faces that are substantially parallel and of dimensions defined by the ISO 7810 standard. The electronic module comprises a support, generally in the form of a film, on which a semiconductor chip such as a microprocessor or an EEPROM is disposed, either directly on the surface of the film or else in a window previously cut out in the thickness of the support. On one face of the support, referred to as the "contact" face, and facing away from the semiconductor chip, electrical contacts are formed to which the semiconductor chip is connected, e.g. by means of connection wires that pass through holes formed in the film. These electrical contacts are intended to provide an electrical link to equipment, such as a card reader, with which the semiconductor chip is to exchange information.
For commercial reasons and for reasons to do with appearance, the main faces of the card body are decorated by means of a graphic, which is usually applied by the well-known technique of offset printing.
In practice, an electronic memory card having a printed graphic is made as follows. A card body is made in which a cavity is formed for receiving the electronic module. The cavity is of dimensions that are larger than those of the module, and it may be obtained by various different methods. For example, the card body is punched out from a laminated plastic sheet, and then machined to form the cavity. The card body can also be made by molding it in a mold recess that includes a projection which forms a space with a volume corresponding to the cavity. If the card body is laminated, a portion can be cut out from a half-card body to form the cavity. After formation of the cavity by one of these methods, the desired graphic is printed on at least one of the main faces of the card body. Finally, the electrical module is mounted in the cavity with an adhesive, and the semiconductor chip is programmed as a function of the intended application, such as pay-phone and bank transactions.
However, this known method of printing an electronic memory card suffers from several drawbacks.
Firstly, the card manufacturer must retain an inventory of printed card bodies, prepared as described above, into which the card manufacturer mounts the electronic module. However, it is difficult to know how many printed card bodies of any particular graphic to order because one cannot predict how many memory cards will be manufactured badly. More specifically, after the electronic module is mounted on the card body, the memory card is tested. It is rejected as unacceptable if the electronic module is glued badly or if the module fails to operate properly. In such a case, the printed card body must be discarded. Thus, to take such an eventuality into account, more printed card bodies must be inventoried then the number of memory cards being manufactured. However, the needed number of printed card bodies is difficult to predict when the printing is done prior to manufacture of the memory card by mounting the electronic module on the card body.
In addition, the stresses exerted on the card body during offset printing make it necessary to provide means for supporting the bottom of the cavity because it is so thin. Otherwise, the card body could be damaged or the graphic could be poorly printed.
Finally, even after printing, the bottom of the card body can still be seen through the empty spaces surrounding the electronic module, because of the gap that exists between the module and the periphery of the cavity. This detracts from the appearance of the memory card.